Ink production system

ABSTRACT

An ink production system constructed with a dyestuff solution producing unit, a dyestuff solution processing unit by execution of chromatographic operations on the dyestuff solution, and an ink preparation unit to effect preparation of ink with the refined dyestuff solution as discharged from the processing unit.

This application is a continuation of application Ser. No. 603,755,filed Apr. 25, 1984, now abandoned; and is related to copendingapplication Ser. No. 925,494, filed Oct. 29, 1986; copending applicationSer. No. 796,515, filed Nov. 8, 1985; copending application Ser. No.795,707 filed Nov. 6, 1985; copending application Ser. No. 925,483,filed Oct. 29, 1986; and copending application Ser. No. 925,493, filedOct. 29, 1986.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an ink production system, and, moreparticularly, it is concerned with an ink production system suitable forpreparing recording liquid (generally called "ink") for use in the inkjet recording apparatus or various writing implements.

2. Description of Prior Art

As the ink to be used for an ink jet recording system which implementsrecording of information by ejecting ink within a recording head throughan ejection orifice by means of vibrations transmitted from apiezoelectric vibrator or other expedients, there have so far been knownvarious dyestuffs and pigments which are dissolved or dispersed in aliquid medium such as water or other organic solvents. There has alsobeen known use of ink similar to the abovementioned one for thosewriting implements such as felt tip pens, fountain pens, etc.

One example of general basic ingredients for such ink may compriseprincipally the following three chief components: water-solubledyestuff, water as the solvent for the dyestuff, and glycols as adesiccation-preventive agent.

The water-soluble dyestuff usually contains a large amount of inorganicsalts such as sodium chloride, sodium sulfate, and so forth. Theseinorganic salts are the by-products formed in the course of thedye-synthesizing reaction, or are positively added as a salting-outagent, a diluent, or a level-dyeing agent.

When the recording ink is prepared with use of such dyestuff containingtherein the inorganic salts, awkward situations would take place: theinorganic salts lower the dissolution stability of the dyestuff in theink to bring about agglomeration and sedimentation of the dyestuff.Further, in the ink jet recording heads and writing implements, if andwhen the ink is evaporated in the vicinity of the ejection orificecausing the liquid composition to change, deposition of the inorganicsalts is induced. These phenomena cause clogging to take place at thedischarge orifice, which should be avoided with the utmost of care.

In order therefore to eliminate such disadvantageous effects, it isnecessary to control the inorganic salts concentration within apredetermined range when producing the ink (in general, it is to belimited to 0.5 wt.% or less with respect to the total ink composition).This control is indispensable when the dyestuff available on the generalmarket, which contains therein inorganic salts as impurities, is usedfor preparation of the ink for ink jet recording as well as for writingimplements.

SUMMARY OF THE INVENTION

In view of the above-described points of problem, it is an object of thepresent invention to provide an ink production system which is capableof producing ink suitable for the ink jet recording apparatus andvarious writing implements by removing inorganic salts contained in thedyestuff solution.

In order to attain the abovementioned purpose, the present inventionperforms refining (salt-stripping) of dyestuff solution by execution ofchromatographic operations, and, with the thus refined dyestuffsolution, the desired ink is prepared.

According to the present invention, in the general aspect of it, thereis provided an ink production system comprising: means for producingdyestuff solution, means for processing the dyestuff solution byexecution of chromatographic operations on the solution, and an inkpreparing unit to carry out ink preparation with the refined dyestuffsolution as discharged from the dyestuff solution processing means.Preferably, the processing means separates inorganic salts from thedyestuff solution by means of chromatography.

The foregoing object and other objects as well as specific constructionand function of the ink producing system according to the presentinvention will become apparent and understandable from the followingdetailed description of a preferred embodiment thereof, when read inconjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic structural diagram of one embodiment of the inkproduction system according to the present invention;

FIG. 2, comprising FIGS. 2A and 2B, is a schematic constructionaldiagram showing one embodiment of the dyestuff refining system in theink production system according to the present invention as shown inFIG. 1;

FIG. 3 is a schematic constructional diagram showing a salt-strippingunit in FIG. 2;

FIG. 4 is a graphical representation showing fractionatingcharacteristics of a chromatographic column;

FIG. 5, comprising FIGS. 5A and 5B is a block diagram showing thecontrol section in the ink producing system shown in FIG. 1; and

FIG. 6, comprising FIGS. 6A and 6B, is a flow chart showing thesequential operations of the salt-stripping unit in the system shown inFIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following, the present invention will be described in detail inreference to the accompanying drawing.

FIG. 1 shows an embodiment of the ink production system according to thepresent invention, wherein a reference numeral 1 designates an inkpreparation tank, into which refined dyestuff solution (to be mentionedlater) is fed from a dyestuff refining unit 2 through a feeding valve 2;water-soluble organic solvent and an additive are also fed from storingtanks 4 and 5 through respective valves 6 and 7; and pure water issupplied through a feeding valve 8. These materials as supplied into theink preparation tank 1 are agitated by an agitator 9 to be made ink.

The quantity of ink produced in the preparation tank 1 is detected by aliquid quantity sensor 10. Also, concentrations of dyestuff andinorganic salts in the ink prepared in the ink preparation tank 1 aredetected by a dyestuff concentration sensor 11 and an inorganic saltsconcentraion sensor 12. On the basis of outputs from these two sensors,there is effected the ultimate quality control (lot control) of theprepared ink. Depending on necessity, the ink with its constituentsregulated to desired values is discharged through a discharge valve 13.

A numeral 14 refers to a control section which takes care of drive andcontrol of every section, and a numeral 15 denotes an operating sectionwhere various display devices and drive switches are provided.

FIG. 2 shows one embodiment of the dyestuff refining system according tothe present invention.

In the drawing, a reference numeral 21 designates a dyestuff feedingsection storing therein dyestuff powder 22. The dyestuff powder 22 isfed from this dyestuff feeding section 21 into a preparation tank 24through a dyestuff feeding valve 23. Also, into this preparation tank24, pure water is supplied through a pure feeding pipe 26 having a purewater valve 25 interposed in one part thereof.

In this preparation tank 24, aqueous solution of dyestuff is prepared bymixing and dissolving the dyestuff powder 22 and the pure water by meansof an agitator 27 installed in the preparation tank 24. The liquidquantity of the aqueous solution of dyestuff staying in the preparationtank 24 is detected by a liquid quantity sensor 28 set in thepreparation tank. The aqueous solution of dyestuff obtained in thepreparation tank contains therein, as the residue, particles of thedyestuff powder which have not been dissolved in the pure water. Thisresidual dyestuff powder is removed by a filter 29. For the filter 29,there may be used ordinary filter paper or "FLUOROPORE" (a trade name ofa product of Sumitomo Denko K.K., Japan, which is made up ofpolytetrafluoroethylene as the principal constituent), and so forth. Theaqueous solution of dyestuff, from which the residual particles, etc.have been removed through the filter 29, is forwarded to a feeding tank31.

The aqueous solution of dyestuff sent into the feeding tank 31 isfurther supplied to a refining section to be described in the followingthrough a feeding pipe 32. A liquid level controlling valve 33 isdisposed in this feeding tank 31 to maintain the quantity of the aqueoussolution of dyestuff to be stored in it to a certain definite level orbelow.

A reference numeral 41 designates a refining section where the inorganicsalts are removed from the aqueous solution of dyestuff. This refiningsection comprises a plurality of salt-stripping units 42 (42-1, . . .42-N). In the salt-stripping units 42, a reference numeral 43 (43-1 . .. 43-N) designates feeding valve opening and closing elements, a numeral44 (44-1, . . . 44-N) refers to salt-stripping filter elements, and 45(45-1, . . . 45-N) denotes discharge valve opening and closing elements.

The feeding valve opening and closing elements (43-1, . . . 43-N) arerespectively connected with aqueous dyestuff solution feeding pipes 47(47-1, . . . 47-N), pure water feeding pipes 46 (46-1, . . . 46-N) andsecondary solution feeding pipes 48 (48-1, . . . 48-N). Into the feedingvalve opening and closing elements 43 (43-1, . . . 43-N), the aqueousdyestuff solution is supplied from the feeding tank 31 through thefeeding pipe 32 and the respective aqueous dyestuff solution feedingpipes 47 (47-1, . . . 47-N), and the pure water through the pure waterfeeding pipes 26 and 46 (46-1, . . . 46-N). Further, the secondarysolution to be mentioned later is fed into the feeding valve opening andclosing elements 43 (43-1, . . . 43-N) from a secondary solution storingtank 51 through a feeding pipe 52 and the respective secondary solutionfeeding pipes 48 (48-1, . . . 48-N).

At the feeding valve opening and closing element 43, it is determinedwhether or not aqueous dyestuff solution, pure water, and secondarysolution as fed thereinto are to be directed into the salt-strippingfilter element 44.

The salt-stripping filter element 44 removes inorganic salts from theaqueous dyestuff solution and the secondary solution supplied thereintothrough the feeding valve opening and closing element 43 bychromatography.

By controlling the discharge valve opening and closing element 45, theaqueous dyestuff solution, the inorganic salts concentration of whichhas become lower than a predetermined value (e.g., 5% by weight withrespect to the dyestuff) by such refining (salt-stripping), isdischarged into a storing tank 56 through discharge pipes 55 (55-1, . .. 55-N). Also, aqueous solution let out from the filter element 44 isdischarged, depending on its component concentration, into an inorganicsalts solution discharge tank 58 or into discharge pipes 59 (59-1, . . .59-N).

One end of the discharge pipe 59 is communicatively connected with asuction port of a circulation pump 60, and the aqueous dyestuff solutionlet out into the discharge pipe 59 is forwarded under pressure by thiscirculation pump 60 into the secondary solution storing tank 51 througha discharge pipe 61 communicatively connected with an outlet port of thecirculation pump 60. In this manner, the dyestuff aqueous solution whichhas been refluxed from the discharge side of the refining section 41 isre-supplied to the refining section 41 as the secondary solution forfurther refining (salt-stripping).

A reference numeral 74 designates a discharge valve disposed in thedischarging tank 58, through which the inorganic salts solution isdischarged.

FIG. 3 illustrates the construction of the salt-stripping unit 42 shownin FIG. 2, wherein a first feeding valve 431 in the feeding valveopening and closing element 43 is controlled for its opening and closingto thereby regulate supply of pure water into the salt-stripping filterelement 44 through the feeding pipe 46. In the same manner, byopen-and-close control of a second feeding valve 432 and third feedingvalve 433, supply of the secondary solution and the aqueous dyestuffsolution into each of the salt-stripping filter elements is regulated.

The salt-stripping filter element 44 separates the inorganic salts fromthe aqueous dyestuff solution by chromatography. In more detail, theaqueous dyestuff solution is fed into the top end part of achromatographic column 441 from the feeding valve opening and closingelement 43. While the aqueous dyestuff solution as supplied is fallingdown within the chromatographic column 441, each of the components inthe aqueous solution is fractionated. By this chromatographicdevelopment operation, those components having the lowest adsorptibilityflow out first. Accordingly, by detecting concentrations of thecomponents in the effluent solution, it is possible to extract only theaqueous dyestuff solution with its inorganic salts concentration havingbeen made lower than a predetermined concentration from the effluentsolution on the basis of the detection results.

An inorganic salts concentration sensor 442 and a dyestuff concentrationsensor 443 are to detect concentration of the inorganic salts and thedyestuff in the effluent solution from the chromatographic column 441,and are disposed within an outflow liquid passage 444 at the bottom partof the column 441. For detecting concentration of each component, thereare various methods such as measurement of electric conductivity,measurement of ion current, measurement of spectral light intensity, andothers, any one of which will meet the purpose.

The refining (salt-stripping) operation is performed in such a mannerthat the dyestuff solution is fed into the chromatographic column 441for every certain definite quantity thereof. For this purpose, a liquidsurface level sensor 445 is disposed at the top end part of the columnso as to control feeding of the aqueous solution from the feeding valveopening and closing element 43 on the basis of the detection results.

For a solid phase to be charged into this chromatographic column 441,there may generally be used an ion-exchange resin, a chelate resin, andso forth. In the embodiment of the present invention, an ion retardingresin such as, for example, "RETARDION 11A-8" (a tradename for a productof Dow Chemical Co.) is used. The ion retarding resin is capable ofeffecting regeneration of pure water without necessity for anyregenerating agents. Also, since the resin is almost neutral, it can beadvantageously used for salt-stripping of those substances which areunstable to acid and alkali.

FIG. 4 is a graphical representation showing effluent curves drawn byplotting the concenration of each component in the effluent solutionfrom the chromatographic column 441 with respect to time (i.e.,fractionating characteristics). As shown in this graphicalrepresentation, the dyestuff concentration (curve I) indicates its peakduring a time period of from T1 to T2, while the inorganic saltsconcentration (curve II) indicates its peak during a time period of fromT3 to T4. In this embodiment, the fractionation of effluent solutionfrom the chromatographic column 441 by the detected values of theinorganic salts concentration sensor 442 and the dyestuff concentrationsensor 443 in utilization of the abovementioned fractionatingcharacteristics.

That is to say, in the case that the dyestuff concentration in theeffluent solution is higher than a predetermined value C2 (effectivedyestuff concentration) and the inorganic salts concentration is below apredetermined value C3 (permissible inorganic salts concentration) (thetime period of from T1 to T2), the effluent solution is introduced intothe storing tank 56. However, when the inorganic salts concentrationexceeds the value C3 and the dyestuff concentration becomes lower thanthe value C2, the effluent solution is introduced into the inorganicsalts solution discharing tank 58. On the other hand, during a timeperiod, wherein the inorganic salts concentration becomes higher thanthe value C3 and dyestuff concentration becomes lower than the value C2(a time period of from T2 to T3), the effluent solution is refluxed intothe secondary solution storing tank 51.

Returning to FIG. 3, the discharge valve opening and closing element 45is to perform segregation of the effluent solution as mentioned in theforegoing, for which purpose the outflow liquid passage 444 is branchedinto three ways, and the branch pipes and the discharge pipes 57, 59 and55 are communicatively connected thorough the first, second and thirddischarge valves 451, 452 and 453, respectively. With such construction,the effluent solution can be discharged into the inorganic saltssolution discharge tank 58 by opening the first discharge valve 451,and, in the same manner, the effluent solution can also be led into thesecondary solution storing tank 51 and the storing tank 56 by openingthe second and third discharge valves 452 and 453.

FIG. 5 is a block diagram for the control section of the refining systemaccording to the present invention shown in FIG. 1, in which a referencenumeral 101 designates a controller to undertake the drive-control ofevery section in the system, a numeral 102 refers to a read-only memory(ROM) storing therein control programs such as the operationalsequences, etc. as shown in FIG. 5, and numeral 103 refers to arandom-access memory (RAM) temporarily storing therein various data.

A reference numeral 104 designates various switches disposed in theoperating section 15, which sends various instruction signals to theconroller 101 through the input/output buffer circuit 105. A numeral 106refers to a display device also disposed in the operating section 15. Areference numeral 107 indicates a drive circuit to perform the displaycontrol of the display device 106 based on the drive signals from thecontroller 101.

In the present embodiment, analog signals are output from the inorganicsalts concentration sensor 442 and the dyestuff concentration sensor443, and, after these signals are converted into digital signals throughthe respective A/D converters 111 and 112, respectively, they are fedinto the controller 101 through an input buffer circuit 113. On theother hand, digital signals are output from the liquid surface levelsensor 445 and are also fed into the controller 101 through the inputbuffer circuit 113.

Reference numerals 121 through 126 designate drive circuits to open andclose the afore-mentioned valves 431, 432, 433, 451, 452, and 453,respectively. These drive circuits are "on-off" controlled by drivesignals supplied from the controller 101 through an output buffercircuit 127.

By the way, since the salt-stripping units 42-1 to 42-N are of theindentical construction, the unit 42-1 alone is shown in the drawing,the remaining units 42-2 to 42-N being omitted from the illustration.

FIG. 6 is a flow chart showing the operations of each processing unit inthe embodiment of the dyestuff refining system of the construction asdescribed in the foregoing.

In the drawing, at the start instruction from the operating section 15in step ST1, the program switch is set in its "off" condition in stepST2. Subsequently, in step ST3, the second and third feeding valves 432and 433 are opened to start feeding the dyestuff aqueous solution in thefeeding tank 31 and the secondary solution in the secondary solutionstoring tank 51 into the chromatographic column 441. These feedingoperations are continued in step ST4 until the liquid surface level inthe chromatographic column 441 reaches the highest position H (refer toFIG. 3) by an output from the liquid surface level sensor 445. As soonas the liquid surface level H reaches the highest position, i.e., assoon as a predetermined quantity of the aqueous solution has beensupplied into the chromatographic column, the operational sequenceproceeds to step ST5, where both feeding valves 432 and 433 are closed.Next, in step ST6 the first discharge valve 451 is opened, whereby theeffluent solution from the chromatographic column 441 begins to bedischarged into the inorganic salt solution discharge tank 58.

In step ST7, determination is made as to whether the liquid surfacelevel in the column is at the lowest position L (refer to FIG. 3), ornot. In a state immediately after feeding of the aqueous dyestuffsolution and the secondary solution, the liquid surface level is abovethe lowest level L, so that the negative determination ("No") is made,and the operational sequence proceeds to step ST8. In the step ST8, thefirst feeding valve 431 is closed, and the operational sequence goes tostep ST 10 where the aqueous dyestuff solution and the secondarysolution are supplied as mentioned above. Immediately after commencementof the chromatographic development within the chromatographic column441, the concentration of each component in the effluent solution is inthe state as shown in FIG. 4 between time zero and T1. Accordingly, inthe ST10, the determination as to whether the concentration valuedetected by the dyestuff concentration sensor 443 is higher than theeffective dyestuff concentration value C2, or not, comes out "No", andoperational sequence proceeds to step ST11. In the step ST11, thedetermination as to whether the concentration value detected by theinorganic salts concentration sensor 442 is higher than the inorganicsalts concentration value C1, or not, comes as "No", and the operationalsequence proceeds to step ST12. In the step ST12, detemination is madeas to whether the program switch is in its "on" state, or not. In thefirst processing loop, the program switch is in the "off" state, so thatthe determination comes out as "No", and the operational sequencereturns to the step ST7. In this manner, the processing loop of ST7,ST8, ST10, ST11, and ST12 is repeated until the determination is made"Yes" at the step ST10.

Incidentally, at the step ST7, when the determination comes out as"Yes", the operational sequence proceeds to the step ST9, whereby thefirst feeding valve 431 is opened and pure water is fed into thechromatographic column 441. As the result of this, the processing loopin such case goes through ST7, ST9, ST10, ST11, and ST12.

In the step ST10, when the dyestuff concentration value of the effluentsolution from the chromatographic column 441 becomes higher than theeffective dyestuff concentration value C2 (refer to FIG. 4, time T1),the operational sequence proceeds to step ST13. In the step ST13, thedetermination is made as to whether the inorganic salts concentrationvalue detected by the inorganic salts concentration sensor 442 is higherthan the permissible inorganic salts concentration value C3, or not.

Here, owing to the chromatographic development operations in thechromatographic column 441, the aqueous dyestuff solution with theinorganic salts having been separated from it flows out first (refer toFIG. 4, time T1 to T2). Accordingly, the determination in the step ST13comes out as "No", and the operational sequence proceeds to step ST14.In the step ST14, the first discharge valve 451 is closed, while, instep ST15, the third discharge valve 453 is opened, thereby the effluentsolution from the chromatographic column 441 passes through thedischarge pipe 55 and discharged into the storing tank 56. Subsequently,the program switch is turned on at the step ST16, and the operationalsequence returns to the step ST7. Thus, by repetition of the processingloop of ST7, ST8, ST10, ST13, ST14, ST15, and ST16 or ST7, ST9, ST10,ST13, ST14, ST15, and ST16, there can be obtained in the storing tank 56the aqueous dyestuff solution with reduced inorganic salts concentrationlower than the permissible concentration value C3. Such processing loopis repeated until the determination comes out as "Yes" in the step ST13.

As shown in FIG. 4, when the outflow of the inorganic salts begins, andthe inorganic salts concentration in the effluent solution increases toa value higher than the permissible inorganic salts concentration valueC3 (vide: FIG. 3, time T2), the operational sequence proceeds from thestep ST13 to the step ST17 so as to close the third discharge valve 453and to open the seocnd discharge valve 452 in step ST18. As the resultof this, the effluent solution is hindered its discharge into thestoring tank 56, and, instead, it is let out into the discharge pipe 59.In this embodiment, if it is assumed that the circulation pump 60 isdriven in synchronism with the opening operation of the valve 452, theeffluent solution is discharged into the secondary solution storing tank51 through the discharge pipes 59 and 61. The reflux of such effluentsolution continues until the determination comes out as "No" in the stepST10. The secondary solution recovered as such is again subjected torefinement for the salt-stripping. Next, when the dyestuff concentrationin the effluent solution lowers and the value becomes lower than theeffective dyestuff concentration value C2 (vide: FIG. 4, time T3), thedetermination comes out as "No" in the step ST10, and the operationalsequence proceeds to the step ST11. At this stage, since the inorganicsalts continues to flow out, the determination comes out as "Yes" in thestep ST11, and the operational sequence proceeds to the step ST19 wherethe second discharge valve 452 is closed, and further the firstdischarge valve 451 is opened at step ST20. As the result of this,reflux of the effluent solution to the secondary solution storing tank51 is stopped, and it begins to be discharged into the inorganic saltssolution storing tank 58 through the discharge pipe 59. Such dischargingoperation continues until the inorganic salts concentration in theeffluent solution becomes lower than the inorganic salts concentrationvalue C1.

When the inorganic salts concentration becomes lower than the value C1(vide: FIG. 4, time T4), the determination comes out as "No" in the stepST11, and the operational sequence proceeds to the step ST12. At thisstage, since the program switch has already been set in its "on" statein the step ST16, as mentioned in the foregoing, the determination comesout as "Yes" in the step ST12, and the operational sequence proceeds tostep ST21 where the first discharge valve 451 is closed and thedischarge of the effluent solution into the discharge tank 58 iscompleted.

Next, in step ST22, the feeding valve 431 is closed and the supply ofpure water into the chromatographic column 441 is stopped. That is tosay, in this embodiment, the first feeding valve 431 is controlled forits opening and closing so that the liquid surface level of the aqueoussolution in the chromatographic column 441 may always be at the lowestposition (cf. FIG. 3), whereby pure water is supplied (steps ST8 andST9). With the supply of pure water, the solid phase in thechromatographic column is washed (regenerated). As mentioned in theforegoing, when the inorganic salts concentration in the effluentsolution becomes lower than the inorganic salts concentration value C1,it is determined that the washing (or regeneration) has been effected,and the pure water feeding is stopped.

After execution of the step ST22, the operational sequence goes backagain to the step ST1 to wait for the start instruction.

In the above-described manner, the first cycle of the refiningoperations (salt-stripping operations) terminates. Incidentally, theoperations in each of the processing units 42-1 to 42-N in thisembodiment are performed in synchronism one another. However, theinvention is not limited to this embodiment alone, but it may also befeasible to execute the processing operations in the sequential manner.

In this embodiment, too, the secondary solution as recorverd is refinedin each processing unit 42. It should, however, be noted that separateprocessing unit for the secondary solution may be provided to effect therefining.

As described in the foregoing, according to the present invention, sincethe refined dyestuff solution, from which inorganic salts have beenremoved by chromatography, is made to be continuously supplied in theproduction of ink, it is possible that the ink of stable qualitysuitable for use in the ink jet recording apparatus and writingimplements is continuously and automatically produced.

We claim:
 1. An ink manufacturing system to produce ink from an aqueousdyestuff solution containing inorganic salt contaminantcomprising:dyestuff solution preparation means for producing a dyestuffsolution; refining means including (a) a chromatographic means forremoving inorganic salt contaminant from said dyestuff solution; (b)transfer means for transferring said dyestuff solution to saidchromatographic means; (c) discharge means for discharging said dyestuffsolution from said chromatographic means; and (d) inorganic salt sensormeans for detecting the inorganic salt concentration in said dischargeddyestuff solution and for generating an output responsive to saiddetected inorganic salt concentration; ink preparation means forproducing ink from said discharged dyestuff solution; control meansincluding (i) comparison means for receiving said output from saidinorganic salt snesor means, for comparing said output with apredetermined value, and for generating an output responsive todifferences between said detected inorganic salt concentration and saidpredetermined value, (ii) fractionation means for fractionating saiddischarged dyestuff solution in response to said output from saidcomparison means into a portion having an inorganic salt concentrationat or below said predetermined value and a portion having an inorganicsalt concentration above said predetermined value; and (iii) circulationmeans for recycling said discharged dyestuff solution portion having aninorganic salt concentration above said predetermined value to saidchromatographic means and for passing said discharged dyestuff solutionportion having an inorganic salt concentration at or below saidpredetermined value to said ink preparation means.
 2. An inkmanufacturing system for producing ink from an aqueous dyestuff solutioncontaining inorganic salt contaminant comprising:dyestuff solutionpreparation means for producing a dyestuff solution; refining meansincluding (a) a chromatographic means for removing inorganic saltcontaminant from said dyestuff solution; (b) transfer means fortransferring said dyestuff solution to said chromatographic means; (c)discharge means for discharging said dyestuff solution from saidchromatographic means; (d) inorganic salt sensor means for detecting theinorganic salt concentration in said discharged dyestuff solution andfor generating an output responsive to said detected inorganic saltconcentration; and (e) dyestuff sensor means for detecting the dyestuffconcentration in said discharged dyestuff solution and for generating anoutput responsive to said detected dyestuff concentration; control meansincluding (i) a first comparison means for receiving said output fromsaid inorganic salt sensor means, for comparing said output with apredetermined salt value, and for generating an output responsive todifferences between said detected inorganic salt concentration and saidpredetermined salt value (ii) a second comparison means for receivingsaid output from said dyestuff sensor means, for comparing said outputwith a predetermined dyestuff value and for generating an outputresponsive to differences between said detected dyestuff concentrationand said predetermined dyestuff value; (iii) fractionation means forfractionating said discharged dyestuff solution in response to saidoutputs from said first and second comparison means into a portionhaving an inorganic salt concentration at or below said predeterminedsalt value and a dyestuff concentration at or below said predetermineddyestuff value, a portion having an inorganic salt concentration at orbelow said predetermined salt value and a dyestuff concentration abovesaid predetermined dyestuff value, a portion having an inorganic saltconcentration above a predetermined salt value and a dyestuffconcentration above said predetermined dyestuff value, and a portionhaving an inorganic salt concentration above said predetermined saltvalue and a dyestuff concentration at or below said predetermineddyestuff value; (iv) circulation means for recycling said dischargeddyestuff solution portion having an inorganic salt concentration abovesaid predetermined salt value and a dyestuff concentration above saidpredetermined dyestuff value to said chromatographic means; and to passsaid discharged dyestuff solution portion having an inorganic saltconcentration at or below said predetermined salt value and a dyestuffconcentration above said predetermined dyestuff value to said inkpreparation means; and (v) an effluent means for removing both saiddischarged dyestuff solution portions having a dyestuff concentration ator below said predetermined dyestuff value.
 3. An ink manufacturingsystem to produce ink from an aqueous dyestuff solution containinginorganic salt contaminant comprising:dyestuff solution preparationmeans for producing a dyestuff solution; refining means including (a) aplurality of chromatographic means in parallel series for removinginorganic salt contaminant from said dyestuff solution; (b) transfermeans for transferring said dyestuff solution to each of saidchromatographic means; (c) discharge means for discharging said dyestuffsolution from said chromatographic means; and (d) inorganic salt sensormeans for detecting the inorganic salt concentration in said dischargeddyestuff solution and for generating an output responsive to saiddetected inorganic salt concentration; ink preparation means forproducing ink from said discharged dyestuff solution; control meansincluding (i) comparison means for receiving said output from saidinorganic salt sensor means, for comparing said output with apredetermined value, and for generating an output responsive todifferences between said detected inorganic salt concentration and saidpredetermined value, (ii) fractionation means for fractionating saiddischarged dyestuff solution in response to said output from saidcomparison means into a portion having an inorganic salt concentrationat or below said predetermined value and a portion having an inorganicsalt concentration above said predetermined value; and (iii) circulationmeans for recycling said discharged dyestuff solution portion having aninorganic salt concentration above said predetermined value to saidchromatographic means and for passing said discharged dyestuff solutionportion having an inorganic salt concentration at or below saidpredetermined value to said ink preparation means.
 4. An inkmanufacturing system for producing ink from an aqueous dyestuff solutioncontaining inorganic salt contaminant comprising:dyestuff solutionpreparation means for producing a dyestuff solution; refining meansincluding (a) a plurality of chromatographic means in parallel seriesfor removing inorganic salt contaminant from said dyestuff solution; (b)transfer means for transferring said dyestuff solution to each of saidchromatographic means; (c) discharge means for discharging said dyestuffsolution from said chromatographic means; (d) inorganic salt sensormeans for detecting the inorganic salt concentration in said dischargeddyestuff solution and for generating an output responsive to saiddetected inorganic salt concentration; and (e) dyestuff sensor means fordetecting the dyestuff concentration in said discharged dyestuffsolution and for generating an output responsive to said detecteddyestuff concentration; control means including (i) a first comparisonmeans for receiving said output from said inorganic salt sensor means,for comparing said output with a predetermined salt value, and forgenerating an output responsive to differences between said detectedinorganic salt concentration and said predetermined salt value, (ii) asecond comparison means for receiving said output from said dyestuffsensor means, for comparing said output with a predetermined dyestuffvalue and for generating an output responsive to differences betweensaid detected dyestuff concentration and said predetermined dyestuffvalue; (iii) fractionation means for fractionating said dischargeddyestuff solution in response to said outputs from said first and secondcomparison means into a portion having an inorganic salt concentrationat or below said predetermined salt value and a dyestuff concentrationat or below said predetermined dyestuff value, a portion having aninorganic salt concentration at or below said predetermined salt valueand a dyestuff concentration above said predetermined dyestuff value, aportion having an inorganic salt concentration above a predeterminedsalt value and a dyestuff concentration above said predetermineddyestuff value, and a portion having an inorganic salt concentrationabove said predetermined salt value and a dyestuff concentration at orbelow said predetermined dyestuff value; (iv) circulation means forrecycling said discharged dyestuff solution portion having an inorganicsalt concentration above said predetermined salt value and a dyestuffconcentration above said predetermined dyestuff value to saidchromatographic means; and to pass said discharged dyestuff solutionportion having an inorganic salt concentration at or below saidpredetermined salt value and a dyestuff concentration above saidpredetermined dyestuff value to said ink preparation means; and (v) aneffluent means for removing both said discharged dyestuff solutionportions having a dyestuff concentration at or below said predetermineddyestuff value.